• 방사성폐기물학회지
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• 제21권1호
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• pp.165-173
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• 2023

Various linear system solvers with multi-physics analysis schemes are compared focusing on the near-field region considering thermal-hydraulic-chemical (THC) coupled multi-physics phenomena. APro, developed at KAERI for total system performance assessment (TSPA), performs a finite element analysis with COMSOL, for which the various combinations of linear system solvers and multi-physics analysis schemes should to be compared. The KBS-3 type disposal system proposed by Sweden is set as the target system and the near-field region, which accounts for most of the computational burden is considered. For comparison of numerical analysis methods, the computing time and memory requirement are the main concerns and thus the simulation time is set up to one year. With a single deposition hole problem, PARDISO and GMRES-SSOR are selected as representative direct and iterative solvers respectively. The performance of representative linear system solvers is then examined through a problem with an increasing number of deposition holes and the GMRES-SSOR solver with a segregated scheme shows the best performance with respect to the computing time and memory requirement. The results of the comparative analysis are expected to provide a good guideline to choose better numerical analysis methods for TSPA.

• 전기학회논문지
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• 제66권3호
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• pp.587-592
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• 2017

In the three-phase four-wire low-voltage power distribution equipment, single-phase and three-phase load have been used mainly mixed. Also linear and nonlinear loads have been used together in the same conditions. In a three-phase four-wire distribution line, the current distribution of three-phase linear load is almost constant in each phase during driving or stopping, but the single-phase load is different from each other for each phase in accordance with the operation and stop. So that the voltage unbalance is caused by the current difference of each phase. In the three-phase four-wire distribution system, non-linear load is used with linear load. The presence of single-phase nonlinear loads can produce an increase in harmonic currents in three-phase and neutral line. It can also cause voltage unbalance. In the present study, we analyzed for the voltage unbalance fluctuations by the operation pattern of the single and three-phase linear and non-linear load in three-phase four-wire low voltage distribution system.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2393-2398
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• 2003

In this paper, we proposes a new fuzzy inference system for modeling nonlinear systems given input and output data. In the suggested fuzzy inference system, the number of fuzzy rules and parameter values of membership functions are automatically decided by using the kernel-based method. The kernel-based method individually performs linear transformation and kernel mapping. Linear transformation projects input space into linearly transformed input space. Kernel mapping projects linearly transformed input space into high dimensional feature space. The structure of the proposed fuzzy inference system is equal to a Takagi-Sugeno fuzzy model whose input variables are weighted linear combinations of input variables. In addition, the number of fuzzy rules can be reduced under the condition of optimizing a given criterion by adjusting linear transformation matrix and parameter values of kernel functions using the gradient descent method. Once a structure is selected, coefficients in consequent part are determined by the least square method. Simulated result illustrates the effectiveness of the proposed technique.

• 전기학회논문지
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• 제56권4호
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• pp.730-738
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• 2007

As well known when the linear machine is operated between two points repeatedly under positioning control, there are various positioning error at the moment of zero speed owing to the non-linear disturbance like as unpredictable friction force. To remove this positioning error, a simple least order disturbance observer is introduced and is actually implemented in this study. Due to this simple algorithm the over-all machine system can be modified to simple arbitrary given one-mass load without any disturbance. So, the total construction process for positioning control system is much easier than old one. Moreover, to generate a proper effective position profile with the limited actual machine force, a very powerful on-line mass identification algorithm using the load force estimator is presented. In the proposed mass identification algorithm, the exact load mass can be calculated during only one moving stage under a normally generated position profile. All presented algorithm is verified with experimental result with commercial linear servo machine system.

• 한국추진공학회지
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• 제19권5호
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• pp.46-51
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• 2015

선형 화약 폭발의 전파 특성예측을 위해 다채널 동시 충격파 센싱 시스템을 개발하였다. 개발된 시스템은 펄스 레이저를 이용하여 초당 1000점에서 충격파 생성이 가능하며, 접촉식 센서를 이용하여 15개 채널에서 동시에 충격파 획득이 가능하다. 특히, 선형 화약의 폭파 시간에 상응한느 각 채널의 시간 지연을 사용자 요구에 따라 적절하게 적용할 수 있는 능력을 갖춤으로써 다양한 선형 화약의 폭발에 의한 충격파 전파를 예측할 수 있을 것으로 기대된다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제49권2호
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• pp.102-109
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• 2000

The magnetically levitated system technology is highly expected to contribute the new transportation system of the 21st century with its high velocity operation, better riding comforts, friendliness to environment and saving of maintenance labour. Its development has been completed in low speed and in high speed application. In 2005, the Transrapid with 430 km/h speed will go into operation between Berlin and Hamburg[1]. In the year 2000, the realization of JR-Maglev will be basically evaluated for commercial operation[2]. In korea, maglev test vehicle with magnet for levitation and single sided linear induction motor for propulsion is under test at 1 [km] test track in KIMM.[3,4] Here, a transverse flux linear motor in combination with the levitation and the guidance leads to a considerable high power density and high efficiency simultaneously. The designed and measured performance of transverse flux linear motor for maglev system revealed a great potential of system mass reduction.

• 한국전자파학회논문지
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• 제12권4호
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• pp.600-610
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• 2001

본 논문에서는 초고속 위성통신 시스템의 채널 특성에 대한 성능 분석을 하였다. 고속 데이터 전송의 열화요인으로 작용하는 군지연과 비선형 분석을 통하여 다양한 전송 서비스를 제공하는 Ka 대역의 초고속 전송 시스템의 채널 성능 영향을 고찰하였다. 전송 데이터가 증가할수록 군지연과 비선형에 의한 영향은 증가하며, 군지연 선형 성분과 비선형의 AM-AM 성분이 시스템 성능 열화에 지배적으로 작용하는 것을 알 수 있었다. 고속 데이터에 따른 광대역 전송 대역폭으로 낮은 군지연과 이득 평탄도를 얻기가 어려우므로 주요 열화 요소를 등화하여 수십 Mbps에서부터 수백 Mbps 의 넓은 범위의 서비스를 동일 시스템에서 효과적으로 제공하여야 한다. 분석된 결과는 최적의 동작점을 갖는 초고속 위성통신 시스템을 설계하고 운용하는데 활용될 수 있다.

• 대한기계학회논문집A
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• 제26권1호
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• pp.15-22
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• 2002

This paper introduces a compensating system for machining error, which is resulted from chucking with separated jaws. In machining the chucked cylindrical workpiece, the deterioration of machining accuracy, such as out-of-roundness is inevitable due to the variation of the radial compliance of the chuck workpiece system which is caused by the position of jaws with respect to the direction of the applied force. To compensate the chucking compliance induced error, firstly roundness profile of workpiece due to chucking compliance after machining needs to be predicted. Then using this predicted profile, the compensated tool feed trajectory can be generated. And by synchronizing the cutting tool feed system with workpiece rotation, the chucking compliance induced error can be compensated. To satisfy the condition that the cutting tool feed system must provide high speed and high position accuracy, brushless linear DC motor is used. In this study, firstly through the force-deflection experiment in workpiece chucked lathe, the variation of radial compliance of chuck workpiece system is obtained. Secondly using the mathematical equation and cutting experiment result, the predicted profile of workpiece and its compensation tool trajectory are generated. Thirdly the configuration of compensation system using linear motor is introduced, and to improve the system performance, PID controller is designed. Finally the tracking performance of system is examined by experiment. Through the real cutting experiment, roundness is significantly improved.

• 대한전기학회논문지
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• 제37권7호
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• pp.490-497
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• 1988

This paper is concerned with the robust stability of linear quadratic state feedback regulators for infinite dimensional systems in the presence of system uncertainties Several robustness results ensuring the asymptoitc stability and exponential stability of the perturbed closed loop system are derived for a class of nonlinear perturbations of the system and input operators satisfying the matching condition. For the case where the input space is finite dimensional, some robust properties of the state feedback regulator designed on the basis of the linear quadratic regulator for finite dimensional unstable modes are also discussed seperately.

• Journal of applied mathematics & informatics
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• 제8권2호
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• pp.659-668
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• 2001

Let S(z) be a power series with operator coefficients such that multiplication by S(z) is an everywhere defined transformation in the square summable power series C(z). In this paper we show that there exists a reproducing kernel Krein space which is state space of extended canonical linear system with transfer function S(z). Also we characterize the reproducing kernel function of the state space of a linear system.